chemistry

Fulgide

Fulgide is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Fulgide rather than just read about it. In short: In organic chemistry, a fulgide is any of a class of photochromic compounds consisting of a bismethylene-succinic anhydride core that has an aromatic group as a substituent. The highly conjugated system is a good chromophore.

Key takeaways

Fulgide belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Fulgide to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Fulgide from memory before moving on to harder problems.

Reference excerpt

In organic chemistry, a fulgide is any of a class of photochromic compounds consisting of a bismethylene-succinic anhydride core that has an aromatic group as a substituent. The highly conjugated system is a good chromophore. It can undergo reversible photoisomerization induced by ultraviolet light, converting between the E and Z isomers, both of which are typically colorless compounds. Unlike the more-stable Z isomer, the E isomer can also undergo a photochemically-induced electrocyclic reaction, forming a new ring and becoming a distinctly colored product called the C form. It is thus the two-step Z–C isomerization that is the photochromic change starting from the stable uncyclized form.

History The first compound of this class was synthesized in 1906 (by Hans Stobbe, using the Stobbe condensation), with the name based on the Latin word fulgere, meaning "to shine", for the shiny and large variety of colors of the crystal. The photochromic mechanism of fulgide was reported in 1968. It was not until 1981 that derivatives of fulgide, which made thermally stable photoisomerization, was reported. By editing both non-aromatic substituents and aromatic substituent, fulgide derivatives that are high in thermal stability and photostability were synthesized.

Derivatives Various other carbonyl structures have been studied, in addition to the original succinic anhydride. The goals include controlling various chemical properties, photochemical properties, and embedding of this structural motif in more complex molecules.

Fulgimide

Fulgimide is an analog that has succinimide instead of succinic anhydride. It has nearly the same photochromic properties, but the imide is substantially more stable than the carboxylic acid anhydride towards hydrolysis. It also involves a less-complicated synthetic process for attaching substituents onto the structural core. The nitrogen atom provides a point of attachment for chains that can be cross-linked to form polymers.

Fulgenolide Fulgenolide is a lactone analog: one of the two succinic anhydride carbonyl groups is replaced by an alkyl link. Fulgenolides have a larger quantum yield than other fulgide derivative and has a λmax of the C form in near IR-region.

Fulgenate Fulgenate is a diester analog. However, fulgenates do not have photochromic characteristics.

References

Illustrations

Worked examples

Example 1 — a first encounter with Fulgide

Start with the simplest possible case. Write down what Fulgide claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Fulgide before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Fulgide ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Fulgide

In research: Fulgide appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Fulgide in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Fulgide is common in secondary-school and first-year university syllabi. It links to neighbouring topics Carboxylic anhydrides, Five-membered rings, Heterocyclic compounds with 1 ring, so understanding it makes those chapters shorter.
In everyday life: Look for Fulgide outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Fulgide in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Fulgide means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Fulgide out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Fulgide in simple terms?

Why does Fulgide matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Fulgide?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Fulgide.